Question: $ A = \left[\begin{array}{rrr}1 & 1 & 0 \\ 2 & 2 & 1 \\ 1 & 0 & 0\end{array}\right]$ What is $ A^{-1}$ ?
Solution: $ = \left[\begin{array}{rrr}0 & 0 & 1 \\ 1 & 0 & -1 \\ -2 & 1 & 0\end{array}\right]$